Fuel injection pump for diesel engines



Jan. 23, 1940. 5 JUHASZ 2,187,732

FUEL INJECTION PUMP FOR DIESEL ENGINES Filed Feb. 14 1936 //1 Van /0/' Patented Jan. 23, 1940 PATENT OFFICE FUEL INJECTION PUMP FOR DIESEL ENGINES Kalman John De Juhasz', State College, Pa.

Application February 14., 1936, Serial No. 63,933

1 Claim.

This invention relates to improvements in fuel injection pumps of the type similar to a number of commercially obtainable pumps such as Bosch, REF, Simms, Benes, Scintilla and others 5 which are characterised by:

(1) One pump element for each engine cylinder;

(2) Cam-operated, spring-returned plunger;

(3) Port-controlled cut-01f l (4) Pump-delivery controlled by rotating the plunger in which a slanting, scroll-shaped control-edge is incorporated for this purpose.

The objects-of .my improvements are, first, to avoid the possibility of wrong assembly of plung- 15 ers, control-sleeves and control-rods; second, to provide an accurate setting for equalizing the delivery of each of the several pump-elementsof a multi-cylindered pump, and, finally, to reduce the cost and increase the accuracy of manufac- 20 ture.

An embodiment of the invention is illustrated in the accompanying drawing which shows the pump parts to which the invention relates, while other essential parts, such as housing, cam, cam- 25 shaft, delivery-valve and others are not shown.

Fig. 1 is a vertical section through a pump-element; Fig. 2 is a cross-section on the line 2-4 through the lower portion of the plungerand control-sleeve; Fig. 3 is a modification of the I ,0 construction shownon Fig. 2; Fig. 4 is a sectional view through line 4-4 through control sleeve and control rod; Fig. 5 is a possible modification of Fig. 4 using two control rods; Fig. 6 is a sectional view through line 6-6 showing the ar- 35 rangement for the accurate adjustment of the tion between the space inside the barrel and the I suction chamber outside the barrel. In order to vary the pump delivery the plunger is rotated around its axis and thereby different portions of the scroll-shaped control edge are brought into eoaction with the cut-oil port. The rotation of the plunger is accomplished by means of the control sleeve 3 the lower portion of which is broached to engage with the correspondingly splined lower end 2b of the plunger. The upper end of the control sleeve is formed as a gear 3a which engages with the toothed control-rod 4. This latter is actuated either manually or automatically by. a governor. In this manner to the 5 spaced. The correct assembly of these. parts is made possible by marking (with a drill-mark or a numeral) the coacting tang and slot on the one hand, and the coacting teeth in the control rod and gear on the otherhand. If, at the assembly, these marks are overlooked, and the parts incorrectly assembled, then the plungers of a multi-cylindered pump will be indifferent angular relationship respectively to their barrelsresulting in diflerent'discharges from the individual pump elements. A further disadvantage is the diflieult and expensive manufacture of the plunger occasioned by the presence of the tangs, and the lack of rigidity of the control sleeve owing to the slot- My construction has the advantage of reduced cost. and increased accuracy of the plunger, because the tangs are eliminated and the plunger can be readily produced by centerless grinding and lapping methods. i The splines, which can be of the shape shown in Fig. 2 and Fig. 3, or modifications of these, can be also produced cheaply and accurately by automatic grinding methods. My construction of the control sleeve 3 results also in reduced cost, increased accuracy and rigidity; the female splines in this element can be produced by broaching. A further advantage of my plunger construction is that it can be made shorter for a given stroke, because the splined lower portion can be made smaller than the plunger diameter, and therefore can enter the barrel l. Shortness of the plunger is a contributing factor to lower cost, increased accuracy and rigidity.

Fiu-thermore, my construction of the plunger and control sleeve positively prevents wrong assembly, because the cross section of the splined portion of plunger and sleeve is such that the two elements fit together in the correct position splines on the plunger, and the corresponding female spline in the control sleeve, diflerent from the rest of the splines, i. e. wider or narrower. In the Figs. 2 and 3 this one spline is wider than the rest. Naturally, however, any other cross section which has not more than one axis of symmetry accomplishes this purpose. If there are two correct relative positions for the plunger and sleeve, then the splined cross section may have two or less axis of symmetry.

My construction prevents the wrong assembly also of the gear 3a and the control rod 4, because the teeth in these are so formed that they can be brought into engagement in only one relative position, i. e. in the correct one. Obviously, any irregular spacing of teeth in the control rod with an equal irregular spacing of gaps in the gear 3a will achieve this result. In my Fig. 4 this result is attained by the simple expedient of making in the control rod 4 one tooth wider than the rest, and in the gear 311 one gap wider than the rest. In Fig. 5 a modification of the control elements is shown in which two control rods engage with, and can be used to rotate the gear 3a. This method eliminates backlash and tends to reduce the side force acting on the control sleeve 3, which results in an improved equality of discharges from a multi-cylindered pump and also in a reduced load on the governor. The feature of preventing wrong assembly is possessed also by the construction shown in Fig. 5, because one of the control rods has a tooth wider than the rest, and the other control rod has one gap wider than the rest and the gear 3a is shaped so as to engage with both rods in one position only.

By the above described constructionalfeatures it is ensured that no coarse error is committed in the assembly of a multi-cylindered pump.

. Even so, in general, there will be a slight, but

pbjectionable difference between the discharges of the individual pump units owing to unavoidable manufacturing inaccuracies in the produc- 'tion of plungers, control sleeves, control rods, and center distances in the housing into which the several pump elements are mounted. In my construction provision is made for the compensation of these manufacturing inaccuracies by altering slightly the angular position of the barrel in its bore in the housing. Thereby the position of the cut-off port lb with reference to the controledge 2a of the plunger can be adjusted to be the same in each pump element and thus the discharges from each equalized. In my construction this result is attained with the aid of two screws 8 and 1 shown in Figs. 1 and 6 which engage with suitably shaped recesses lo and Id formed in the barrel I. Byunscrewing one screw and screwing in the other a slight rotation can be given to the barrel until the correct position is found in which the discharges from all pump units are equal. In this position both screws are driven home, and one set of them, sat the right side (screw 1 in our case) sealed in this position. Should a disassembly of the pump be desirable the left-side set (in Fig. 6 the screw 6) is released and then the barrels can be removed. At reassembly the barrels are replaced and the left-side set of screws (screw 6 in Fig. 6) tightened again whereby the original setting is restored. Disassembly and reassembly are possible because the ends of the screws 6 and l are located outside the circle of the lower portion of cylinder I which has a reduced diameter.

I claim:

In a fuel injection pump in combination, -a body, a barrel inserted into the said body, a plunger operating within said barrel as a pump for the pressure delivery of fiuid, inlet and bypass ports on the barrel and co-acting edges on the plunger controlling the beginning and end of fluid delivery, a control-sleeve coaxially surrounding a portion of said barrel, said barrel having stepped outside diameters along its length, the diameter of said barrel fitting into said body being larger than the diameter of the adjoining portion of said barrel which is surrounded by said control-sleeve, two axially extending notches formed on that portion of said barrel that fits into said body, said notches extending into the shoulder formed between said larger and said smaller diameter barrel portions, two screws threaded into said body the screw axes being in a plane perpendicular to the axis of said barrel and each screw abutting with its and against one of said notches on said barrel, said screws being capable of rotating said barrel in opposite senses around the axis of said barrel with reference to said body for the purpose of fine adjustment of the quantity of delivery, the ends of said screws being outside of the smaller diameter of said barrel adjoining to that larger diameter which fits into said body whereby endwise removal and replacement of said barrel into said body becomes possible upon loosening oneof said screws and without disturbing the setting of said barrel as fixed by the other screw.

KAh-MAN JOHN DE JUHASZ. 

